25th January, 2018 at 4.00 PM -Seminar- Speaker: Mr. Rajesh Dutta Title Stochastics of Enzyme Kinetics from Single Molecule Spectroscopy: Fluctuations of Turnover Times as Origin of Non-exponential Dynamics

Stochastics of Enzyme Kinetics from Single Molecule Spectroscopy: Fluctuations of Turnover Times as Origin of Non-exponential Dynamics

Date & Time: Thursday 25th January, 2018 at 4.00 PM
Venue: SSCU AUDITORIUM
Abstract:
Understanding the working of an enzymatic cycle is important in a large number of biochemical processes. [1, 2] Despite a large body of work, several aspects of the details of enzyme’s functions remain shrouded in mystery. In particular, the working of the catalytic cycle is poorly understood. In the recent times, single molecule spectroscopy has allowed direct temporal probe of enzymatic function. An intriguing aspect of the study is the discovery of the fluctuations in the turnover times of product released by a single enzyme molecule. [3] Thus, the interval or the waiting time between the observations of two product molecules is a distribution. Conventional chemical kinetics fails to explain single molecule experimental observations. This distribution of turnover time is reflected in the multi-exponential behavior in single molecule experiments. Even an exponential behavior can sustain a distribution. One needs multidimensional free energy surface to capture role of conformational dynamics in enzyme catalysis. [4] Multistep modeling of enzyme reactions scheme quantitatively explains the mean turn over time. However, it fails to explain randomness of the enzymatic turnover times for beta-galactosidase enzyme. Renewal reaction kinetics provides quantitative explanation of randomness parameter. [5, 6] Moreover, one can obtain additional information such as mean survival time of enzyme-substrate (ES) complex, non-Poisson reaction dynamics of ES complex, probability of backward and catalytic reaction that are beyond the reach of available theoretical models.